Safety device for machine tool

Abstract

A safety device for a machine tool includes a machine, a main controller, a detection unit, a warning system, a drive circuit and a temporary stop device. The detection unit includes a contact sensing element and a non-contact sensing element. After the detection unit is induced and triggered by a charged body, a sensing signal is generated and transmitted to the main controller and interpreted by the main controller to drive the warning system, and the drive circuit transmits an analog signal to a charged body of the temporary stop device to rotate a motor of the machine in a reverse direction for a brake. The present invention provides a double sensing protection device with both contact and non-contact sensing effects to improve the safety of using the machine tool and prevent operators from being injured.

1 . A safety device for a machine tool, comprising:
 a machine, having a saw blade installed thereon and driven by a motor to rotate;   a main controller, for determining an induced trigger status to generate an analog signal;   a detection unit, electrically coupled to the main controller, and comprising:
 a contact sensing element, being an electrostatic charge sensor, and using a grounding line and a Darlington trigger method to sense a signal of a charged body, and setting a threshold of the electrostatic charge sensor as a reference value, and creating an induced trigger when an electric charge is different from the reference value; and 
   a non-contact sensing element, being a capacitance sensor, and forming an induced space magnetic field, and forming an induced trigger when the charged body approaches the induced space magnetic field, and after the detection unit is induced and triggered, a sensing signal is transmitted to and interpreted by the main controller;   a warning system, electrically coupled to the main controller, for turning on the warning system after the analog signal is received;   a drive circuit, electrically coupled to the main controller, for transmitting the analog signal to drive a brake; and   a temporary stop device, electrically coupled to the drive circuit, for rotating the motor in a reverse direction immediately after the analog signal is received.   
     
     
         2 . The safety device for a machine tool as recited in  claim 1 , wherein the warning system includes a warning light and an alarm. 
     
     
         3 . The safety device for a machine tool as recited in  claim 1 , wherein the electrostatic charge sensor is installed at the axis of the saw blade, so that the saw blade becomes a sensing component, and the capacitance sensor is installed at a position in front of the saw blade. 
     
     
         4 . An operating method of the safety device for a machine tool as recited in  claim 1 , comprising the steps of:
 resetting the detection unit to discharge electrostatic charges of the electrostatic charge sensor, setting a threshold of the detection unit as a reference value, and resetting the capacitance of the capacitance sensor;   determining an induced trigger status by the main controller;   turning on the temporary stop device to brake the motor in a reverse direction after a trigger is induced;   turning on the warning system to produce warning sound and light simultaneously;   discharging the electrostatic charges of the electrostatic charge sensor, setting the threshold to a reference value, and resetting the capacitance of the capacitance sensor after a troubleshooting is completed;   determining whether or not the resetting process is completed by the main controller;   simultaneously cancelling the warning system to turn off both warning sound and light; and   releasing the temporary stop device to resume the operation of the motor.   
     
     
         5 . The operating method of a safety device for a machine tool as recited in  claim 4 , wherein the steps of discharging the electrostatic charge of a first sensor and resetting the capacitance of the second sensor include a delay time provided for the main controller to determine whether or not the procedure is completed.